Air compressor tank drain valve



D. WILKERSON 2,662,551

AIR COMPRESSOR TANK: DRAIN VALVE File May 7, 1951 AJV l9 m x 4.

y z\\ 7a 22 INVENTOR' DEWEY VV/LKERSON ATTORNEY Patented Dec. 15, 1953 UNITED STA'l'E tATENT @FFECE Dewey Wilkerson, Denver, (3010., assignor to Wilkerson Corporation, Denver, 0010., a, corporation of Colorado Application May '7, 1951, Serial'No. 224,991

1 Claim. 31

This invention relates to fluid pressure operated valves and particularly to an air pressure responsive valve for automatically draining off all accumulated water, oil, and sludge deposits in the air storage tank of an air compressor.

An object of the invention is to provide an air tank drain valve of simple, rugged construction operative from an intermitting pressure air line for the automatic expulsion at tank pressure of accumulations of water, oil, sludge and other foreign matter therein. Other objects will he apparent to persons skilled in the art.

It is to be understood that the instant disclosure is illustrative of one embodiment by which the invention is reduced to practice, and that any desired changes and modifications consistent with the scope of the invention as claimed may be made in the details of the structure as shown.

The single figure of the drawing is substantially a central vertical sectional View through a drain valve comprising the invention.

As here shown, my novel valve comprises a substantially frusto-conical housing made up of a base section 5, an intermediate section ii, a top section 17, and an attaching nipple 3 by which the valve is connected with the bottom of a compressed air storage tank 9. The housing interior is divided into three non-communicating compartments by a lower flexible diaphragm ll between the base and intermediate sections and by an upper flexible diaphragm i2 between the intermediate and top sections. These diaphragms are clamped at their marginal portions between meeting edge flanges on the respective sections in the conventional manner of diaphragm mounting. The base a is dished from its upper face to constitute a lower air compartment l3 beneath the diaphragm i i, and the intermediate section 6 is oppositely dished from its bottom face to eon-, 1 stitute an intermediate air compartment M between the two diaphragms. The interior of the top section 7 above the diaphragm l2 constitutes an upper air compartment it open to the atmosphere through a breather port it and closed at its top by a thickened wall portion ll of the housing section 1.

The intermediate section 5 is formed with an integral interior wall iii inset slightly from the top face of the section and provided with a central air passage 59. This wall forms a retainer for the upper end of an expansion spring 25.! which bears at its lower end on a circular foot plate 3| that engages the central portion of the diaphragm I i to press it down flatly against the fiat bottom of the air compartment it. The bias of spring 2i! is sufficient to maintain the diaphragm H flexed downwardly against the bottom of the compartment in the position shown when air in the compartment I3 is substantially at atmospheric pressure.

The base compartment !3 is adapted for open communication with an interrnitting pressure air line, not shown, through an air inlet 2 I, and may optionally be provided with a double acting check valve '22 controlling a drain cook 23 to the atmosphere. Air may enter the compartment id between the two diaphragms by way of an inwardly opening check valve 2% in the wall of the section 5, and is bled to the atmosphere through an adjustable needle valve assembly 25 also in the wall or the section.

An axial drainage bore 25 is provided through the apex portion of the top section l in communication at its lower end through a port 2? with a radial sediment discharge passage 23 which opens to the atmosphere through the thickened wall portion ll of the section. The port 2? is surrounded by a valve seat which receives a valve head 29 on the upper end of an axial stem at mounted for reciprocation in the wall portion i i. The stem to extends within the compartment IE5 and at its lower end carries a circular foot plate 3! which seats flatly on the diaphragm l2 and biases it to flex downwardly under the expansive force of a coil spring 32 which surrounds the stem. The lower end of the spring bears on the foot plate 3! and its upper end seats against a washer t3 nested in a recess in the underface of the Wall portion I 'i. The washer serves also to retain in place a packing ring 34 or" rubber or other suitable material around the valve stem to seal it against leakage from the passage is into the compartment l5.

The attaching nipple 8 has threaded connection with the apex portion of the section l and is externally threaded at its upper end for detachable connection in the bottom of the tank 93. An axial bore 35 extends through the nipple and receives therethrough an upper valve stem 36 coaxial with. the stem til. The stem 35 is adapted for reciprocation in the bore 35 with ample clearance to provide free drainage from the tank into the relatively larger bore 25 of the top section of the housing. A valve 3? on the upper end of the stem cooperates with a seat on the upper end of the nipple 8 to control the bore 35; and adjacent its lower end the stem carries a cross pin 38 that provides a seat for the lower end of an expansion spring 39 surrounding the stem with its tank.

upper end bearing against a shoulder formed by a lateral enlargement of the bore 35. The lower end of the stem 85 normally is spaced above the upper end of the stem 39.

In the illustrated normal position of the parts, the two valves 29' and 3? are closed tightly against their seats through the downward pull exerted on their stems by the respective springs 32 and 39, doubly closing the drain passage from the The valve constitutes an inner seal within the casing and the valve it constitutes a safety seal at the tank outlet. Also in the illustrated normal position, air in all three compartments is, it, and i5 is at atmospheric pressure. When air under intermittent source pressure enters the base compartment is through the inlet 21 it immediately flexes the diaphragm upwardly against the bias of the sprin 2% and compresses the air in compartment This compressed air acts through the aperture is to lift the diaphragm E2 and valve stem 33? and open the valve 29. During its upward travel the upper end of the stern up and lifts the stem 36 to open the valve 3i and permit accumulated water, sludge, and oil on the tank bottom to blast at tank pressure through the passage comprising the bore bore and passage 23 to the atmosphere. The lower diaphragm remains in its upwardly flexed position for as long as source pres sure continues in the compartment it, which may be from a few seconds to several hours depending upon the type of installation.

Duration of the discharge blast from the tank is determined by appropriate adjustment of the needle valve 25 to regulate the rate at which air can escape from the compartment i i and thus permit i-eseating of the valves 31' and 25 by action of their respective springs. As air bleeds from the compartment Hi the upper diaphragm i2 flexes downwardly, regardless of the position of the lower diaphragm l i, and the valve stems are correspondingly lowered until their respective valves are fully reseated, with the valve 3? closing slightly before the valve 29. This relative overtravel between the two valves permits full drainage of the discharge passage and assures closure thereof even though one valve should for some reason fail to seat properly at the time. When the intermittent line source pressure in the compartment is is relieved, the spring 25 immediately flexes the diaphragm downwardly to its original position, with the check valve 2t opening automatically to allow entry of air from the atmosphere behind the diaphragm if inflow past the needle val is insufficient.

imp ant feature of the invention is the fact that re arm of th upper diaphragm :2 to its original position, with consequent reseating of the valves 29 and 3?, is governed entirely by release of air past the valve which can be set for any des'red time interval. Nothing mechanical can interfere with return of the diaphragm, and it is unaffected by pressure conditions in the line compartment 13.

From the foregoing description it is apparent that in its broad aspects the invention embodies a pair of valves spaced apart axially in the tank drain passage and spring loaded to close in the direction of discharge flow therethrough. One valve has an overtravel relative to the other and also constitutes an actuator for moving it to open position. The actuator valve operates in response to pressure difierential in two compartments in one of which air from the ambient atmosphere is compressed by the application of air at line pressure in the other to provide fluid motor means for moving the actuator valve, and through it the other valve, to open position. A third compartment has a collapsible wall flexing under air pressure in the motor compartment to move the valves into open position, from which they return to closed position under their spring bias at a rate of travel determined by the regulated escape of compressed air from the motor compartment.

I claim:

A compressed air tank drain valve comprising a housing having a base section, a top section, and an intermediate section, said base section having an inlet for communication with an intermittent pressure air line, said base and intermediate sections being oppositely dished from their adjacent faces, a first diaphragm secured between the base and intermediate sections and separating their interiors into a first compartment in open communication with the air inlet and a second compartment in restricted communication with the ambient atmosphere, a second diaphragm secured between said intermediate and top sections as a wall of said second compartment, said top section having a tank drain passage therethrough and a valve controlling said passage, means in said top section common to both said valve and said second diaphragm and biasing the valve to closed position and said second diaphragm to a position of fiexion inwardly of said second compartment, means in said second compartment biasing said first diaphragm to a position of fiexion outwardly of the second compartment and into the first compartment, said first diaphragm flexing into the second compartment in response to application of air at line pressure through said air inlet whereby to compress the air in the second compartment and thereby flex said second diaphragm outwardly to open said drain passage valve, and an air release valve in a wall of said intermediate housing section adjustable to regulate release of compressed air from said second compartment and thereby determine the rate of closure of the drain passage valve in response to its biasing means.

DEWEY VVILKERSON.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 294,674 Richter Mar. 4, 1884 2,509,597 Hamilton May 30, 1950 2,548,236 Parks Apr. 10, 1951 FOREIGN PATENTS Number Country Date 11,396 England 1885 18,688 England 1906 

